An immense volume of tailings and tailings water is accumulating in tailings ponds located on mine leases in the oil sands area of Alberta, Canada. Oil sands mining companies have proposed to use tailings- and tailings water-amended lakes and wetlands as part of their mine remediation plans. Polycyclic aromatic hydrocarbons (PAHs) are substances of concern in oil sands tailings and tailings water. In this study, we determined concentrations of PAHs in sediments, insect larvae and adult insects collected in or adjacent to three groups of wetlands: experimental wetlands to which tailings or tailings water had been purposely added, oil sands wetlands that were located on the mine leases but which had not been experimentally manipulated and reference wetlands located near the mine leases. Alkylated PAHs dominated the PAH profile in all types of samples in the three categories of wetlands. Median and maximum PAH concentrations, especially alkylated PAH concentrations, tended to be higher in sediments and insect larvae in experimental wetlands than in the other types of wetlands. Such was not the case for adult insects, which contained higher than expected levels of PAHs in the three types of ponds. Overlap in PAH concentrations in larvae among pond types suggests that any increase in PAH levels resulting from the addition of tailings and tailings water to wetlands would be modest. Biota-sediment accumulation factors were higher for alkylated PAHs than for their parent counterparts and were lower in experimental wetlands than in oil sands and reference wetlands. Research is needed to examine factors that affect the bioavailability of PAHs in oil sands tailings- or tailings water-amended wetlands.

The Athabasca River drains an area of 160 000 km2 in northern Alberta, Canada, with much of the lower basin underlain by oil-sand deposits. The oil sands occur primarily in the McMurray Formation of the Cretaceous Period, with outcrops evident along the banks of the Athabasca River, as well as the lower portions of several tributaries. Since the oil sands represent a natural diffuse source of hydrocarbons to the aquatic environment, understanding the nature and extent of sediment-bound hydrocarbon contaminants in the context of the sediment regime of the Athabasca River is important. Described are fluvial geomorphic characteristics of the lower Athabasca River, which provide a basis for assessing sediment-bound hydrocarbon contaminants. Suspended sediment derived from main stem and tributary sources between Fort McMurray and Embarras account for 1.2 Mt, or 18%, of the mean annual load of the Athabasca River. Of this load, approximately 53% of the sediment input originated from tributaries, the remainder from main-stem sources. The majority of sediment contributed along the main stem occurs in the vicinity of Embarras, well downstream of oil-sand sources. Natural oil-sand sediment contributions are likely much less than 3% of the annual load downstream of Fort McMurray. Key words: sediment, fluvial geomorphology, oil sands, hydrocarbons, polycyclic aromatic hydrocarbon (PAH), contaminants, environmental monitoring, Athabasca River.

Many of the organochlorine pesticides that were once widely used have either been banned or uses have been restricted in Canada and the United States. Near areas of high pesticide use at mid-latitudes in eastern North America, environmental levels of some of these pesticides peaked in the 1960s, and all have declined at least since the late 1970s. We determined depositional trends in a midlatitude temperate glacier in Alberta, western Canada (52°N, 117°W). In contrast to trends in eastern North America, ∑DDT, dieldrin, and ∑chlordane reached peak concentrations (2.57, 0.05, and 0.07 ng/L, respectively) and maximum flux to this cold high elevation environment in the 1980s at least 1 decade after they had been banned and maximum use had occurred in North America. From 1959 to 1995, a significant decline was evident for R-HCH (r 2 ) -0.64, p < 0.001). A significant severalfold increase and positive trend (r 2 ) 0.17, p < 0.03) was evident for hexachlorobenzene with maximum flux occurring in the 1990s. Lindane and ∑chlordane had a distinct bimodal depositional pattern with peak concentrations occurring about 1960 and again in 1989. Meltwater from glaciers may contribute high concentrations of pesticides to cold aquatic ecosystems for decades or centuries.

We determined levels of Se, As, Cd, Pb, and Zn in aquatic insects at coal mine-impacted and reference sites in streams in the Rocky Mountain foothills of west central Alberta from 2001-2003. Selenium levels were greater at coal mine-impacted sites than at reference sites in caddisflies but not in mayflies or stoneflies. Arsenic levels were greater at coal mine-impacted sites than at reference sites in caddisflies and stoneflies but not in mayflies. Zn levels were higher at coal mine-impacted sites than at reference sites in all three groups of insects. At coal mine-impacted sites, Se levels in mayflies and caddisflies were greater than those in stoneflies while at reference sites mayflies contained greater concentrations of Se than either caddisflies or stoneflies. Arsenic levels in mayflies were greater than those in caddisflies at reference and coal mine-impacted sites and were greater than those in stoneflies at reference sites. At both types of sites Cd differed amongst insect taxa in the order of mayflies > caddisflies > stoneflies. The same was true of Zn at coal mine-affected sites. At reference sites, stoneflies had greater concentrations of Zn than both mayflies and caddisflies. At both types of sites, Pb levels were greater in mayflies and caddisflies than they were in stoneflies. Of the five trace elements considered in this study, only Se was sufficiently elevated in aquatic invertebrates to be of potential concern for consumers such as fish and aquatic birds. Such was the case at both coal mine-impacted and reference sites.

Several oil sands mines and refineries are currently recovering oil from the Athabasca River region near Fort McMurray, Alberta. Planning and construction of additional oil sands mines are in various stages of completion. Due to environmental concerns for aquatic life in areas downstream from current and future oil sands activities, surveys were conducted between 1998 and 2000 to determine whether the quality of water and sediments in tributaries of the Athabasca River are affected by flowing through reaches with exposure to natural oil sand deposits. This paper presents the results for metals in bed and suspended sediments collected from the Mackay, Steepbank, and Ells rivers during those surveys. The suspended sediments had a clay content (n = 7) ranging from 36.2% to 65.0%, while bed sediments, which consisted of a predominant sand fraction, had percent clay (n = 39) ranging from 0.0% to 38.1%. A Mann-Kendall non-parametric analysis to assess the longitudinal trend of the metals in the bed sediments found no significant (alpha = 0.05) downstream trend in the Mackay or Steepbank rivers; however, the Ells River displayed a generally decreasing tend from upstream to downstream. The results provide no indication that metal concentrations in the bed sediments and/or suspended sediments of the Mackay, Steepbank, and Ells rivers increase significantly as the three tributaries flow through reaches that have natural oil sand exposures (McMurray Formation).